UPDATE: A number of progressive and get-out-the-vote groups have begun responding to Grimes. Here’s a scathing statement from MoveOn calling on Grimes to pull down the ad:

This latest TV ad from Alison Lundergan Grimes is deeply upsetting. Grimes seems to be forgetting that we are a nation of immigrants that has continually strived to honor all the hard-working people who aspire to the American Dream. MoveOn members in Kentucky and across the country are contacting millions of voters to help prevent a Republican takeover of the Senate, and it makes that important work harder when Democrats embrace inflammatory Republican rhetoric. It’s deeply troubling that Grimes would stop this low in order to try and defeat McConnell, and she needs to take this offensive advertisement off the air immediately. It’s long past time to reform our broken immigration system, and we need elected officials who will work toward a pathway to citizenship for millions for aspiring Americans.

And Democracy for America:

The Grimes campaign must take down this offensive ad. It’s simply wrong for any Democrat to use right-wing talking points and dehumanize struggling immigrant families. Democracy for America members have been proud to work with allies to end Mitch McConnell’s 30-year career in Washington and save the Senate from Republican control, but every moment Secretary Grimes fails to remove this hurtful ad ignores the plight of millions and makes our work more difficult.

With respect to how to handle the cross currents of the immigration debate, the choice for Democrats in swing states and districts comes down to this: 1) talk like a Republican in hopes of defusing the issue in the middle (and if you’re really hard line, muddying the waters on the issue in hopes of depressing the turnout of immigration hawks for your opponent); 2) lean into the issue by supporting bipartisan comprehensive immigration reform in hopes of connecting with the pragmatism of gettable voters and their frustration with the status quo.

In the two southern Senate races where Democrats are challenging Republican incumbents, the different choices made are on full display. In Kentucky, Democratic Senate candidate Alison Lundergan Grimes is up with a new ad that attacks Mitch McConnell on “amnesty” (due to McConnell’s support for the Immigration Reform and Control Act of 1986 under President Reagan). Grimes has said she supports comprehensive immigration reform, which led to attacks by the main outside group supporting McConnell. Now she seems to be going hard right. Meanwhile, in Georgia, Michelle Nunn has remained a steadfast supporter of the bipartisan comprehensive immigration reform bill passed by the Senate in 2013 and has called immigration one of the “sharper contrasts” between her and Republican nominee David Perdue. She is leaning into the issue to drive home her message that her opponent is too extreme to find bipartisan solutions on a range of issues.

Based on polling and experience, which strategy is more likely to work?

Back in the 2010 cycle, we took a hard look at this question. Hart Research conducted polling on behalf of America’s Voice in four moderate to conservative states – Arkansas, Colorado, Missouri, and Ohio – to test the electability of Democratic candidates who stood up and planted their flag in favor of comprehensive immigration reform. The comprehensive immigration plan was described as the Obama/Democratic plan. After being described, it was subjected to attacks: it’s “amnesty;” we should secure the borders first; it hurts Americans who are unemployed; it will cost taxpayers billions in taxpayer-funded services. The results? After being attacked, voters maintained their support for comprehensive immigration reform by 14 percentage points. Even more remarkably, following the back and forth debate, Democrats improved their ratings on their ability to handle immigration by 16 percentage points. In fact, earned legalization is not a vulnerability; it’s immigration reform’s most popular provision.

The experience in elections also favors those candidates who lean in, take a stand and defend it. In 2006, 2008, 2010, and 2012, attempts by Republicans to demagogue immigration proved to be a colossal failure in each cycle, while candidates who leaned into the issue prospered. For example, in the most competitive 2008 House races where candidates expressed stark differences on immigration, pro-comprehensive immigration reform Democrats won 20 of 22 races. In 2010, Senators Harry Reid and Michael Bennet were clear examples of candidates who leaned in and won surprising victories in a very tough year for Democrats.

According to Frank Sharry, Executive Director of America’s Voice:

Grimes’ ad smacks of desperation. By trying to get to McConnell’s right, Grimes jeopardizes her attempts to define herself as a leader who will tackle tough problems with bipartisan solutions. Democrats should leave it to Republicans to be the anti-immigrant party that has fought tooth and nail to block an immigration reform proposal supported by a strong majority of American voters.